Masking process for the production of photographic images



2 Claims. (c1. 965) This invention relates to a process for the production of colored photographic images having improved colors as well as to a photographic material for performing this process.

In many operations carried out in the reproduction art, the necessity exists of exposing the light-sensitive film with colored light. Thus, the color separation records for a three-color reproduction are exposed with blue light (yellow separation record), green light (magenta separation record) and red light (cyan separation record); furthermore, masks for color reproduction are generally produced with colored light, usually with yellow or yellow-orange light. Colored light is also sometimes used in black-and-white reproduction, for example, in the reproduction of originals which have become yellowed, where a yellow or yellow-orange filter is to be used, or in the reproduction of colored toned images.

It is common practice to use in these processes colored filters, which transform the white light of the light source (arc light, incandescent light, xenon light etc.) into the required colored light.

However, the use of filters always produces certain disadvantages in practice; due to their surface reflection or due to scratches, flecks of dust and finger marks, they cause scattered light; the waviness of thin filters, such as can occur because of climatic influences with gelatin filters, leads to distortions of the image; thick filters, such as glass filters, displace the plane of focus, these all being influences which have an eifect on the quality of the reproduction; in addition, the interposition of filters into the path of rays requires a separate working step. These disadvantages are especially serious with processes for the color correction of colored photographic images.

It is among the objects of the present invention to avoid the disadvantages described above and to provide a very simple and inexpensive technique for the production of photographic images having true colors.

It has now been found that for the production of photographic images by means of light-senstitive films, the exposure of which must be effected with light of specific spectral distribution, more especially for the production of masks for the reproduction of color images, a lightsensitive film which carries the. light-sensitive layer on one side of the transparent film support and a filter layer on that side which is remote from the outside of the light-sensitive layer (inner side of the sensitive layer) which light absorption provides the necessary spectral distribution for the exposure of the light-sensitive layer.

The said color filter layer can be arranged on the back of the film support or also between the film support and light-sensitive layer. It is also possible for the film support itself to be suitably colored. The color layer is preferably capable of being decolorised automatically in the photographic baths, so that the processed image is colorless at. theclear areas. Dyestuffs which satisfy this United States Patent ice requirement are widely known and in fact in all possible colors from which further colors can then be produced by suitable mixing when required.

The light-sensitive layer itself has a spectral sensitivity which extends at least through the transmission range of the colored filter layer, but preferably beyond said range.

The following example will serve to explain this:

The reproduction of color transparencies using blackand-white masks, can in known manner be carried out in accordance with two different processes.

(1) Only one mask made by contact printing is produced and this mask is brought in register with the original and remains on the original in the production of all color separation records. This mask is usually produced with yellow or yellow-orange light.

(2) Three masks are produced, one with blue light, the second with green light and the third with red light, a specific mask being used in this case for a specific color separation.

For the first-mentioned process, there is used for producing the mask -a light-sensitive material which, in accordance with the present invention, comprises a yellow or yellow-orange filter layer which is on that side of the support opposite to the emulsion layer and through which exposure is made in the production of the mask, a light source with unfiltered (white) light being used. The light-sensitive silver halide emulsion layer itself is sensitive for all parts of the visible spectrum, i.e. is panchromatic.

However, the same material can also be used for the second process, where the masks must be produced with other light colorings. In this case, the production of the masks takes place in known manner, in that the material described is now exposed from the side of the lightsensitive layer and with the use of corresponding color filters.

It is apparent from the example how the panchromatic masking film known per se and to be exposed with filters can be used universally by means of the invention without any modification being made in the processing step in the photographic bath.

The present process is not limited to the example described. It can be used generally and in fact always when one and the same light-sensitive layer for one purpose in the reproduction art must be exposed with a certain type of light and for the other purpose with one or even several types of lightin the latter case, with different filters, while in the former case, the filter is even unnecessary if the layer has the corresponding spectral sensitivity.

Instead of being used on one light-sensitive layer, the invention can also be used on two or more layers which are arranged superimposed and are to be exposed simultaneously, as are known in the reproduction art or also in color photography.

The light-sensitive layer can be either 'a so-called continuous tone layer (with a gradation below 3.5) or also a hard emulsion for line or screen exposures (gradation above 3.5), more especially an emulsion of the so-called lith-type. As well as the silver halide, it can also contain one or more color components, so that a pure color image or also a color silver image can be produced by the method of so-called chromogenic development. Such colored silver images can be used with advantage as masks. Also tanning relief images can be produced if the layer exposed according to the invention is developed with one of the known tanning developers.

The filter layer can have a low color density or even ahigh color density and in the latter case it simultaneously acts as an anti-halation layer when the film is exposed from the emulsion side.

Furthermore, it can contain light-dispersing agents or can be provided with a surface matting, so that the images produced according to the process contain a certain degree of lack of sharpness, as is necessary for example with masking images for color correction.

The light source used for the exposure can either emit white light, or it may also emit colored light for example mercury lamps. In this connection, in a manner analogous to the, use of white light the spectral transmission of the colored layer have to be adjusted to the radiation of the light source to be used.

Light-sensitive films which can be exposed through the support are certainly known in the reproduction art, and in some cases even those which comprise a colored layer in a weakly neutral color on the support. They are used for screening black-and-white half-tone originals. In this case, the exposure with light must not be effected with colored light of pie-determined spectral distribution, but for the highest possible utilisation of the sensitivity of the light-sensitive layer with white light of highest possible intensity, for which reason the coloring of the colored layer is neutral grey and of low density. On the other hand, there are used for the present invention light-sensitive materials which must be exposed with colored light of predetermined spectral distribution, this spectral distribution being produced by suitable coloring of the filter layer of the material in conjunction with the light of the light source which is used for the exposure of the material.

Example A transparent support of acetyl cellulose having a thickness of 200 is coated with a colored antihalo layer. tion of gelatin containing yellow, red, and green antihalo dyestuffs, being decolorizable in photographic processing baths. The antihalo dyestuffs have to be applied in such an amount that the dried antihalo layer shows the following color density: 2.0'for blue light, 1.0 for green light, and 0.35 for red light.

The measuring of the color density is accomplished by interposing colored filters between the light source and the antihalo layer, e.g., color separation filter No. 352L (blue), No. 54L (green), No. 45L (red) of Agfa Aktiengesellschaft.

The thickness of the dried antihalo layer is 8 Numerous antihalo dyestuffs suitable for the process according to the invention are available. Yellow dyestuffs are described for example in the US. patent specification 2,03 6,546 in particular in the Examples 1-5, red dyestuflis in the British patent specification 900,094, and green dyestuffs in Ger-man patent specification 616,007. Suitable is further the dyestufl dysulphine green B (Schultz Farbstofi-Tabellen No. 767). Further dyestulis are disclosed in the British patent specifications 695,874, 633,114, 706,084, 680,631, 506,385, 584,482, 694,681. Onto this colored antihalo layer is cast a protecting layer of gelatin, having a thickness of approximately 11L.

Thereafter the other side of the support is coated with a light-sensitive silver halide gelatin emulsion described in FIAT Final Report No. 360, page 28 which before casting has been diluted with a 7% aqueous gelatin solution in a proportion of 1:1. The light sensitive layer having a thickness of 6.5; was panchromatically sensitized by the addition of suitable sensitizers. Again at protecting layer was applied on to the light-sensitive emulsion layer.

The light-sensitive photographic material described above is processed as ltollows: The photographic material is exposed through a multi-color transparency being in The casting solution consists of a 7% aqueous solucontact with the colored antihalo layer of that material. Accordingly the light-sensitive layer is remote from the light sources. The exposure was accomplished by the aid of an incandescent lamp having a color temperature of 2850 K. Thereafter the exposed photographic material is developed in a common black-and-white developer until a gradation of 0.50 is obtained. The developer has the following composition:

Water ml 1000 Metol -g 7.5 Hydroquinone g 3.5 Potassium bromide g 3 Sodium carbonate (anhydrous) g 30 Sodium .sulphite (anhydrous) g 40 The developing time using a diluted developer (1 part developer and 1 part water) was 3 minutes.

The developed photographic material was rinsed, fixed in an acid fixing bath, rinsed again and dried.

The resulting photographic image is combined in register with a colored transparency whereby the black-an-d-white image is arranged on the back of the transparency.

The desired color separation records for the photornechanical reproduction are prepared from the combina tion transparency+black and white image using for each separation record suitable colored separation filter.

What we claim is:

1. A process for producing color corrected color separation records of multicolor photographic images which consist of yellow, magenta and cyan partial images which comprises (a) exposing to a multicolor photographic image illuminated with white light a light-sensitive photographic material comprising :a light-sensitive silver halide emulsion layer that is sensitive to red, green and blue light and a filter layer having a density to blue light of about 2.0, to green light of about 1.0 and to red light of about 0.35 being capable of being decolorized in photographic processing baths upon a transparent support in such a manner that the filter layer faces the light source,

(b) developing, fixing and drying the exposed lightsensitive material to decolorize the filter layer and produce a silver masking image therein that is negative with respect to the multicolor photographic image,

(c) bringing the fixed and dried material which contains the silver masking image into register with the multicolor photographic image,

(d) producing color separation records by exposing other light-sensitive photographic materials to the silver masking image and the multicolor photographic image that are in register with each other, using for each color separation record an appropriate colored light, and,

(e) developing, fixing and drying the thus exposed photographic materials.

'2. A process as defined in claim 1 in which the filter layer of the light-sensitive photographic material is on the side of the transparent support that is opposite tothat containing the silver halide layer and in which the silver masking image produced in the light-sensitive material has a gradation of about 0.5.

References Cited by the Examiner UNITED STATES PATENTS 1,867,301 7/1932 Baker 9669 1,897,846 2/1933 Kelley 9669 1,900,877 3/ 1933 Hickman 96-84 1,908,527 5/1933 McMaster 9684 1,923,485 8/ 193 3- Hebbel 9684 2,083,672 6/1937 Seymour 9684 (Other references on following page) I 5 UNITED STATES PATENTS Carroll et a1. 9669 Miller 9669 Schneider et a1 9684 Hanson 966 McQueen et a1 9-6-84 Thompson 9669 6 Gaspar et a1. 9669 Harsh 96--6 Straley 9669 Burgardt et a1 9684 Geiger et a1. 9684 NORMA-N G. TORCHIN, Primary Examiner.

J. T. BROWN, Assistant Examiner. 

1. A PROCESS FOR PRODUCING CORRECTED COLOR SEPARATION RECORDS OF MULTICOLOR PHOTOGRAPHIC IMAGES WHICH CONSIST OF YELLOW, MAGENTA AND CYAN PARTIAL IMAGES WHICH COMPRISES (A) EXPOSING TO MULICOLOR PHOTOGRAPHIC IMAGE ILLUMINATED WITH WHITE LIGHT A LIGHT-SENSITIVE PHOTOGRAPHIC MATERIAL COMPRISING A LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER THAT IS SENSITIVE TO RED, GREEN AND BLUE LIGHT AND A FILTER LAYER HAVING A DENSITY TO BLUE LIGHT OF ABOUT 2.0, TO GREEN LIGHT OF ABOUT 1.0 AND RED LIGHT OF ABOUT 0.35 BEING CAPABLE OF BEING DECOLORIZED IN PHOTOGRAPHIC PROCESSING BATHS UPON A TRANSPARENT SUPPORT IN SUCH A MANNER THAT THE FILTER LAYER FACES THE LIGHT SOURCE, (B) DEVELOPING, FIXING AND DRYING THE EXPOSED LIGHTSENSITIVE MATERIAL TO DECOLORIZE THE FILTER LAYER AND PRODUCE A SILVER MASKING IMAGE THEREIN THAT IS NEGATIVE WITH RESPECT TO THE MULTICOLOR PHOTOGRAPHIC IMAGE, (C) BRINGING THE FIXED AND DRIED MATERIAL WHICH CONTAINS THE SILVER MASKING IMAGE INTO REGISTER WITH THE MULTICOLOR PHOTOGRAPHIC IMAGE, (D) PRODUCING COLOR SEPARATION RECORDS BY EXPOSING OTHER LIGHT-SENSITIVE PHOTOGRAPHIC MATERIALS TO THE SILVER MASKING IMAGE AND THE MULTICOLOR PHOTOGRAPHIC IMAGE THAT ARE IN REGISTER WITH EACH OTHER, USING FOR EACH COLOR SEPARATION RECORD AN APPROPRIATE COLORED LIGHT, AND (E) DEVELOPING, FIXING AND DRYING THE THUS EXPOSED PHOTOGRAPHIC MATERIALS. 